The long term goal of the research is to develop interventional radiological procedures to treat congenital cardiopulmonary disease, and to investigate functional and morphological sequelae from their use. Animal studies are designed to: (1) assess mechanoelectrical events of chronic left and right ventricular hypertrophy and to evaluate the extent to which these abnormalities influence the response to non-surgical valvuloplasty procedures; (2) to extend the potential clinical applications of intravascular stents with an emphasis on congenital cardiac disease and pediatric cardiopulmonary applications; and, (3) to extend the applications of angioplasty balloon approaches to atrial septostomy. For the first area of work, dogs with hypertrophied left and right ventricles will be used to evaluate the relationship between acute altered mechanical loading via aortic valve occlusion. Monophasic action potential duration, after-depolarizations, and ventricular ectopy will be monitored. In addition, left and right ventricular force-interval relationships will be established for the hypertrophied heart. In the second project, intravascular stents will be evaluated in pigs for their potential clinical use in the pulmonary, vena caval, and aortic vessels. The ability to dilate stented segments will be evaluated. In addition, stents will be evaluated as a means of maintaining patency of the ductus arteriosus. In the last project, the application of fixed diameter angioplasty balloon dilataion procedures for atrial septostomy will be evaluated in newborn lambs and compared to the Rashkind technique. All of the projects should improve our knowledge regarding the application of nonsurgical transcatheter interventions to treat congenital cardiopulmonary disease. The proposed research is a natural extension of previous work this laboratory has done in developing and evaluating new transcatheter cardiac interventional procedures.